Police initially thought that robbery may have been a motive because Mike and Karen - seen here on a security camera - had been at a local casino before the murder and had won some money.

Credit: Shawnee County District Attorney's Office

Police ruled out robbery when they found $1,300 in cash along with Mike's Rolex watch and Karen's diamond jewelry untouched in the house.

Credit: Shawnee County District Attorney's Office

Topeka police surmised that this was a crime of passion. They refocused their investigation on anyone with a grudge against Mike and Karen. It wasn't long before one name came up: Dana Chandler.

Credit: Sisco family

Dana Chandler was Mike Sisco's ex-wife. They were married for 15 years and went through a drawn out and bitter divorce.

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Dana Chandler lost custody of their children, Hailey and Dustin, to Mike Sisco.

Credit: Sisco family

Mike and his sister, Cathy Boots. Cathy says that Dana stalked Mike and Karen. According to Cathy and other family members, Dana would show up at soccer games, Karen's house, Mike's house, and family get togethers.

Dana's surprise appearances became so frequent that Mike started keeping a record of them in his day planner.

Credit: Sisco family

Just one month before the murders, Mike, left, told his sister, Cathy, and his brother, Tim, that he had come home from work and had found Dana inside his breezeway. Mike claimed that Dana wanted to get back together and he told her that he was marrying Karen.

After Mike's death, his son, Dustin, was raised by his paternal grandmother, Carol Sisco, pictured here. Hailey lived with her boyfriend's family.

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Hailey Sisco with her boyfriend, Chris Seal. They are still a couple.

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When Det. Richard Volle spoke to Dana Chandler, she told him that she had spent the Saturday before the murders more than 500 miles away at home in Denver, Colo. The next day, Chandler told police she went hiking in the mountains taking this route.

Credit: Shawnee County District Attorney's Office

Police became suspicious when they learned that Dana Chandler had purchased two gas cans - like the ones pictured - that Saturday, but had neglected to mention it in her detailed alibi. Police now suspected that Chandler had driven from Denver to Topeka to murder Mike and Karen and had used the gas cans to avoid stopping in Kansas.

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Dana Chandler's black Mitsubishi.

Credit: Shawnee County District Attorney's Office

Detective Volle sent cops along route 1-70 hoping they would find someone that had seen Dana Chandler. It was at this truck stop in WaKeeney, Kansas, that they found a cashier who said she was 70 percent certain she had seen Chandler that night.

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Detective Volle took his findings to the district attorney at the time, but the D.A. didn't think there was enough evidence to bring to a jury. The Sisco-Harkness murder case would go cold.

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For years, the Harkness and Sisco families tried to keep the case alive. Cathy Boots placed posters of Dana Chandler everywhere hoping for a lead.

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Hailey Sisco also joined in on the efforts. For years, she secretly recorded her own mother in the hopes that Dana Chandler would confess or reveal something that could be used as evidence.

In 2008, six years after the murder, the turning point in the case came in a pizza shop. That's where Det. Richard Volle ran into Chad Taylor, who was running for the DA's office. Volle urged Taylor to look into the case if he won the election.

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When Chad Taylor won the election and took office in January 2009, he made good on his promise to Det. Volle and took a hard look at the circumstantial case together with Chief Deputy D.A. Jacqie Spradling.

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In October 2009, "48 Hours" aired the original broadcast publicly naming Dana Chandler as the prime suspect. In this picture, our late colleague Harold Dow confronts Chandler.

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After working the case for over two years, D.A. Chad Taylor decided he had enough to make an arrest and went to Duncan, Okla., to nab Dana Chandler.

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Dana Chandler was living in a pull-up trailer behind her sister's house in Duncan, Okla.

Credit: Shawnee County District Attorney's Office

As the Kansas and Oklahoma authorities prepared to arrest Dana Chandler at her trailer, she left home. Authorities made the arrest in an Arby's parking lot.

Dana Chandler's trial began in March 2012. In opening statements, Prosecutor Jacqie Spradling painted Chandler as a woman scorned and bent on revenge.

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Mark Bennett, Dana Chandler's lawyer, points out that there is no physical evidence - no DNA, no fingerprints, no fiber, no hair - that links Chandler to the crime scene or even places her in the state of Kansas.

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The first witness for the prosecution was Karen Harkness' father, Harold Worswick. Harold, waited 10 long years for this day and considered getting his daughter's case to trial his "job".

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One of the cruxes of the prosecution's case is Dana Chandler's lack of alibi. The weekend of the murders, she was off the radar for 27 hours and authorities learned she gave two versions of where she was during that time.

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In her first version, Dana Chandler said she had spent the night at home on Saturday night and had driven through Rocky Mountain National Park the next day (Photo 21). In her new version, Chandler told a friend she spent Saturday camping and had slept in her car. This map shows her new route.

Credit: Shawnee County District Attorney's Office

Prosecutors contend that both versions of Dana Chandler's stories are lies. In version one, her car was not seen on any of the three surveillance cameras at the entrances of Rocky Mountain National Park. In version 2, Chandler did not see or smell any smoke from the historic forest fires that had blackened the landscape in 2002.

Credit: Shawnee County District Attorney's Office

The one constant in Dana Chandler's stories is that she wound up in Loveland, Colo., on Sunday afternoon where receipts show she bought gas and a change of clothes. According to Chandler, she had started her menstrual cycle and ruined the clothes she had been wearing.

Credit: Shawnee County District Attorney's Office

Prosecutors have an interesting theory to explain how Chandler ended up in Loveland. According to this map, they believe that after the murders in Topeka, Chandler then used the gas cans to get her out of Kansas and into Nebraska. In Nebraska, they believe she bought more gas and then drove straight to Loveland, Colo., and refilled her car one more time.

Credit: Shawnee County District Attorney's Office

But the "Nebraska route" is only a theory and not allowed as evidence at trial since there is no direct proof that Dana Chandler did any of this. And making things more difficult for the prosecution, their truck stop eyewitness, who was almost certain she had seen Chandler the night of the murders, died in 2006.

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With no eyewitness and no forensics, the State must rely largely on motive. And prosecutors believes that Dana Chandler's motive was rage - rage that Mike Sisco had moved on and was going to marry Karen Harkness.

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Mike Sisco and Karen Harkness loved the great outdoors and camping. They had purchased some country property where they hoped to build a home one day.

Credit: Sisco family

Mark Boots, Mike Sisco's brother-in-law, wants to testify about their last conversation. While on this fishing trip - which took place a week before Mike's death - death, Mike told Mark that he was afraid of Chandler and that if he was found dead "Dana Chandler did it."

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Mark Boots can't testify to this conversation with Mike Sisco since it is considered hearsay. In this picture, Mike Sisco is seen fishing. This is the last time that Mark Boots saw him alive.

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The two biggest witnesses for the prosecution are Dana Chandler's own children. Here, Dustin Sisco testifies about how his mom would use him and his sister to spy on their father.

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Hailey Sisco testifies that her mother was "obsessed" with her father and Karen Harkness. A good deal of her testimony centers around the secret recordings she made of her mother.

According to the prosecution, Dana Chandler stalked Mike Sisco and Karen Harkness in person and on the phone. In this graph, Deputy D.A. Jacqie Spradling points out that in the seven months prior to their deaths, Chandler called Mike and Karen 645 times.

Mark Bennett says that it is his client that has been stalked relentlessly for over nine years and that is no evidence that puts Dana Chandler in the State of Kansas or Karen Harkness's residence.

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Mark Bennett argues that police ignored other suspects and points out that there was an unidentified hair found on one of the bullet casings. Bennett claims that it could belong to the real killer.

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As the case goes to the jury, the victims' families worry that the jury may find reasonable doubt and set Dana Chandler free. But their anguish is short-lived, and the jury comes back with a verdict in 83 minutes.

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Dana Chandler is found guilty of two counts of first-degree murder.

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At her sentencing, Chandler, representing herself, denied that she killed Mike Sisco and Karen Harkness or that she ever stalked them.